The average distance from it to the sun is about 58 million kilometers, and the closest is about 46 million kilometers, which is about 100 million kilometers closer than the distance from the earth to the sun.

Mercury transit

This is the picture when Mercury transits. A small star of Mercury flew past the sun quickly. Mercury is the closest planet to the sun in the solar system. The average distance from it to the sun is about 58 million kilometers, and the closest is about 46 million kilometers, which is about 100 million kilometers closer than the distance from the earth to the sun.

The sun seen on Mercury

On Mercury, we will see such a big sun. This is 3 times larger than the sun we see on Earth. It can be seen how close Mercury is to the sun. Is Mercury the closest planet to the star in the universe? Of course not. There are some planets in the universe that are so close that we feel outrageous.

As of November 16, 2020, scientists have discovered 4374 exoplanets . Most of these exoplanets are very close to the stars they orbit. This is because such exoplanets are most easily discovered.

Pegasus 51b

Pegasus 51b

In October 1995, astronomers discovered the first planet outside the solar system. It is named Pegasus 51b. The planet is about 51 light-years away from Earth. Astronomers have discovered that the planet's cycle of orbiting a star only has four Earth days. The earth surrounds the sun for a week, which we call 1 year. If we regard the orbital cycle of the planet around a star as one year, then the one in the exoplanet Pegasus 51b is only 4 days.

Pegasus 51b's orbital period is so short, an important reason is that it is too close to the star. The distance between Pegasus 51b and the orbiting star is only about 7.88 million kilometers. This distance is much closer than the distance between Mercury and the Sun. Pegasus 51b orbits the star Pegasus 51 is a star that is very close to the sun.

Pegasus 51b and the sun on earth

If we have the chance to stand on Pegasus 51b, we will see a very large sun. Its apparent diameter will reach 10°, which is 19 times the size of the sun's apparent diameter we see on Earth. So close to the star, Pegasus 51b has been tidally locked, and one side of it always faces the orbiting star Pegasus 51. The temperature on this side is as high as 1000℃.

Proxima b

Proxima b

Proxima is the closest star to the sun. Its distance from the sun is only 4.22 light years, about 40 trillion kilometers. In August 2016, astronomers also discovered a planet next to Proxima Centauri, named Proxima Centauri b. Proxima Centauri is considered to be an -type earth planet . It is estimated that the mass of Proxima Centauri is about 1.2 times that of the Earth and the radius is 1.1 times that of the Earth. Astronomers have discovered that the orbital period of Proxima Centauri is only 11 days. Therefore, the distance from Proxima Centauri is very close, only about 7.2 million kilometers.

Proxima Centauri b and Earth

What kind of scene will you see on Proxima Centauri b? Will you also see an extremely huge sun like you would on Pegasus 51b? Proxima Centauri is a much smaller red dwarf star , which is much smaller than the sun. Its diameter is only 200,000 kilometers, only one-seventh of the diameter of the sun. However, due to the close distance, the Proxima Centauri we see on Proxima b is three times larger than the sun seen on Earth, which is similar to the sun seen on Mercury.

Because it is too close to the star, Proxima Centauri is tidally locked. Like Pegasus 51b, it is also always facing Proxima Centauri. On this side of it facing Proxima Centauri, the red Proxima Centauri hangs high in the sky and will never fall.

Kepler1b

Kepler1b

In August 2006, astronomers discovered an gas planet in the Milky Way , which is 750 light years away from the earth, called Kepler1b. Its distance from its orbiting star is only about 4.83 million kilometers, and its orbital period is only two and a half days. Kepler 1b is a gas planet with a mass of about 1.2 times that of Jupiter and a diameter of about 1.3 times that of Jupiter. The surface temperature is about 980°C. Astronomers were surprised to find that the planet had a very low albedo, and it was a planet that was darker than charcoal.

Kolo7b

Kolo7b

The planets mentioned above are very close to the stars they orbit, so that the orbital period is only a dozen days or even a few days. However, the exoplanet discovered by astronomers in February 2009 has a period of less than one day. This means it is closer to the stars than the aforementioned planets. This exoplanet is called Colo 7b, about 390 light years from Earth. Colo 7b is only 2.54 million kilometers away from its orbiting stars. Its orbital cycle is only 20 hours. The diameter of this planet is about 1.7 times that of the Earth and its mass is about 5.6 to 11 times that of the Earth. This suggests that it may be a rocky planet.

Colo7b

A rocky planet is so close to a star, what is the scene above? First, it is also tidally locked. The temperature on the side of its star is as high as 1000~1500℃ when the star is roasted. Such temperatures are sufficient to melt the rocks on the surface. In addition, due to the heating of the tidal force of the star, its interior is also very hot. On the star-facing side of Cro 7b, we will see oceans formed by rolling magma , violently erupting volcanoes, and even rock rain. The other side of Crow 7b is shrouded in eternal darkness because it is facing away from the stars. This description may not be accurate, as the red light from the volcano erupts will occasionally cut through the suffocating darkness.

Krolo7b

is 2.54 million kilometers away from the stars. How big is the sun you see on Krolo7b? Crow 7b rotates around the star Crow 7. The diameter of Crow 7 is 1.2145 million kilometers, which is 87% of the diameter of the sun. On the planet Cro 7b, we will see a large sun with an apparent diameter of 25.6°. This is 48 times larger than the apparent diameter of the sun we see on Earth. How terrifying this is! No wonder the surface of Crow 7b was roasted and melted.

Kepler-78b

There are also more outrageous planets than Colo 7b! Kepler-78b discovered in November 2013 is only 1.37 million kilometers away from the star. It only takes 8 and a half hours in the year above. This planet is 400 light years away from Earth, 1.2 times the volume and 1.7 times the mass of Earth. Kepler-78b is the closest planet to the star discovered so far. Because it is too close to the star, it is subject to additional care by the star Kepler-78, and the planet's surface temperature exceeds 2000℃. Its existence seems to allow us to see the scene of the sun expanding to the earth 7.6 billion years later.

Kepler 78b

Kepler-78b's revolution speed reached 281 km/sec, 1.01 million km/h, almost 6 times the revolution speed of Mercury. It is so close to the star that it must maintain an extremely high revolution speed to avoid falling into the star. But some scientists believe that Kepler-78b will be pulled over by Kepler-78 within 3 billion years and will eventually be torn into pieces and fall into stars.

These exoplanets are all very close to the stars they are surrounding. They are all closer to the stars they orbit. This actually makes the solar system very alternative. Careful friends will find this problem: Why do these exoplanets that are very close to stars contain a b in their names? What's going on? Friends who are familiar with it can give you some popular science in the comment section!